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Delivering record-breaking performance offshore
Shell and Qatar Petroleum achieved record times for drilling wells in Qatar’s North Field at the Pearl GTL project — resulting in significant savings — using an approach we call simultaneous operations, or SIMOPS.
With the cost of rigs and personnel running at tens of thousands of dollars a day, cutting down on drilling time made good commercial sense. Before Pearl, the industry considered completing a production well in the North Field in 75 days a good performance. Twenty-two wells for Pearl GTL were completed in an average of 45 days. The fastest well completion took just 28 days.
The drilling crew saved a total of more than 600 days of drilling time compared to previous performance when drilling was complete in April 2010, resulting in a savings of $46 million in costs.
Roger Nobel Lewis
Drilling a well and then getting it ready for production usually happens in two stages: firstly drilling and completing the well, and secondly getting it ready to produce.
Using SIMOPS techniques, Shell worked on two wells at the same time — getting one well ready to produce while drilling the next. The company drilled a total distance of 97 kilometres in the rock below the seabed, constructing wells containing enough steel to build two-and-a-half Eiffel Towers.
Almost every feature of a conventional rig had to be re-thought to achieve SIMOPS. The new design had to accommodate more staff on the main rig, and separate power, air and water supplies.
The platform legs were first put in place offshore. Temporary decks installed on each platform leg made it possible to carry out the entire second stage of the operations — getting wells ready to produce — at the same time that the first stage — drilling and completing wells — was conducted by larger mobile drilling rigs in position over the temporary decks.
The team also delivered a record-breaking safety performance, with no time lost to injury during drilling, platform construction and installation.
The two platforms — Pearl 1 and Pearl 2 — operate 60 kilometres offshore north-east Qatar. The topsides, or permanent decks, built in Dubai, were lowered on to the platform legs in March and November 2010. Each topside is the size of a 10-storey office building and weighs 2,200 Tons, equal to 800 Toyota Land cruisers.
Each platform has 11 wells extending deep under the seabed to the North Field. Two 76–centimetre (30-inch) diameter pipelines link the platforms to the Pearl GTL plant onshore.
As all natural gas for Pearl GTL is processed onshore, only simple, relatively small platforms are needed offshore. Operators in Pearl GTL’s control room in Ras Laffan run the unmanned platforms.
Maintenance workers reach the platforms on a type of vessel never before used in the Gulf. Thrusters on the bow of the “Bourbon Gulf Star” help manoeuvre it safely alongside the platforms to offload cargo, or to transfer passengers.